Fuse plug



Jan. 3, 1939. I LUDWK; 2,142,361

FUSE PLUG Filed May 25, 1935 A TTOR.\'EYS. v

Patented Jan. 3, 1939 UNITED STATES PATENT OFFICE FUSE PLUG Louis Ludwig, Brooklyn, N. Y.

Application May 25, 1935, Serial No. 23,465

2 Claims. (Cl. 200-130) The invention relates to electrical fuse plugs thread prevents the withdrawal of the body and to the manufacture of electrical fuse plugs, member from a solid mould. and more particularly to a method for securing In the present invention the thread may be the metal screw-shells on such fuse plugs. The dispensed with entirely so that the body mem- 5 invention has for its main object to provide a new be! has an external cylindrical wall and may be 5 and novel manner in which to rigidly secure the manufactured at a much lower cost than was formetal screw-shell to the fuse plug, so as to efmerly P 1 8, a d made in moulds of much fectively prevent it from turning or becoming Simpler and cheaper construction.

loose. Another object is to provide a method R ference is now had to the drawing in which which will greatly reduce the cost of the moulds the b y memb f a fus pl is wn at 10 l d, as 11 as th m uld d parts u ed in the screw shell at H, the center contact at I2,

uch appliances, and which will in general reduce the interior recess at l3 and the fusible metal link he cost of manufacturing and assembling the at [4. The fuse illustrated is made of Bakelite appliances. Another object is the provision of nd the whole body member ID is formed in one is an improved 1 t 1 fuse plugin which a piece and provided with the customary transl5 stantial arcuate solder extension from a substanparent mica disc 15 a metal ring 15 o Setial solder body both assures an electrical circuit Curing the mica disc in the ess The lower and is effective in practice to secure the threaded Part 0f the body member is ll ed Without shell on a cylindrical body member against the customary thread to leave an external cylin- 20 moval therefrom drical wall and the screw shell is merely forced 20 These and various other objects and advanon thls tages will be readily understood from the follow- In the constmctlon Of the Ordmary fuse, one

mg description and from the accompanying draw end of the fusible link I4 is generally soldered to ing of a preferred embodiment of the invention, in t P t as shown at while an open which, however, modifications may be made withmg 18 fc'rmed m the y m through which 25 out departing from the Scope of the appended the other end of the fusible link is passed so that claims In the drawing it may be soldered to the screw shell to make the Fig. 1 is a cross-sectional, side elevation of a ggzz i i g i a z f fg fi an e screw s e e presen illiiseedplug to which the invention has been ap 1913, lg c l y ih the i t l g link i 30 1 ewise so ere o e cen er con ac and o O 2 g i gZ ?g Wlth part the screw shell H, but instead of merely having Fig. 3 is a top view shown with the customary a opemng m the body member as 15 mica disc and metal removed ordinar ly the case, a regular pocket 20 substan- F 4 is a o s t o a t p w ta on tlally wider than the link Mus formed which has n g a d vertical side walls and WhlCh has an external Fig 5 is a side elevation of the solder construc- 3553 3 i gg gfigiggg figg z 2;? i g fi tion employed for holding the metal shell in place. the link has g inserted d i i s While the drawing illustrates and the specificaplaced in t t t th metal Shell, (mant on des b a fuse plug, it Will be understood tity of solder is heated to a temperature higher that this invention may be applied to other elect th melting i t d i poured i t th trical appliances on which a screw shell is emp ket, a shown at 2|. ployed in a similar manner to which it is em- Not only does this solder secure the end of the ployed on a fuse plug. link to the metal shell but the temperature of the 5 The ordinary fuse plug may be made of porcesolder is such that a quantity of the solder flows lain, glass, Bakelite, or some other plastic mainto the thread of the shell and forms a partial terial, and to assure that the screw shell is firmly but substantially arcuate thread as shown at 22. secured to the body member, a thread is mould- Sufficient solder adheres to the shell so as to ed on the lower end of the body member. The make it utterly impossible to unscrew the shell 50 moulding of this thread adds considerably to the from the body member; the part of solder 2i expense of manufacturing the body member, which is formed in, fills, and rigidly held in the particularly when the body member is made of pocket 20, acting as an anchor. In Fig. 3, two Bakelite or like materials. Such materials repockets have been shown to indicate that when quire the use of so-called split moulds, as the required a plurality of pockets may be used. 55

However, I have found that the use of one pocket formed as described above is generally suificient. While I have mentioned the use of solder and while I prefer to use that in connection with fuse plugs to assure a perfect electrical contact between the screw shell and the fusible link, it is evident that in many cases a hard-setting plastic material may be used with the same result, particularly, if a plurality of pockets are used.

From the foregoing it will be seen that this construction will effect a great saving in the cost of the moulds; that, in decreasing the weight of the body member, it will save material which is of great advantages in cases of Bakelite and similar materials; and that, inasmuch as the link [4 must be soldered to the metal shell even when the body member is provided with a thread, the pouring of the solder does not, in the case of fuse plugs, involve an additional operation.

The improved fuse plug is strong and durable in practice, and may be manufactured at low cost.

Having described the invention and its objects, what I claim as new and wish to protect by Letters Patent is:

1. An electrical fuse plug including a body portion of moldable insulating material having an interior recess and an externally smooth and cylindrical wall on the lower portion of the body, a shell whose walls are in the form of screwthreads tightly fitting said wall, a pocket formed internally of the body and having an opening through the external cylindrical wall, the opening having a vertical extent at least equal to the distance between two screw threads, said pocket having vertical side walls, one end of fusible link extending through said pocket and contacting said shell, and a solid body of solder filling said pocket and extending internally of one of said threads arcuately a sufiicient distance to securely anchor said shell against removal from said body member.

2. An electrical fuse plug including a body portion of moldable insulating material having an interior recess and an externally smooth and cylindrical wall on the lower portion of the body, a shell whose walls are in the form of screwthreads tightly fitting said wall, a pocket formed internally of the body and having an opening through the external cylindrical wall, the opening having a vertical extent at least equal to the distance between two screwthreads, said pocket having side walls, one end of afusible link extending through said pocket and contacting said shell, and a solid body of solder filling said pocket and extending internally of one of the threads arcuately for a substantial part of the circumference of the shell whereby the shell is substantially anchored on the cylindrical wall against removal therefrom.

LOUIS LUDWIG. 

